Safecracker

Hint: Last safe combination:
Go to the violet room. Unlock the doors with all the triple keys. Enter the doors to discover a secret room with the last safe. The combination is "3528".

Hint: Resetting puzzles:
If you need to reset a puzzle, back away from it, then zoom in on it again. Note: Do not leave while cracking a three-key safe until all three keys are in your inventory as this may cause one to be lost.

Hint: Room 5: Abraham's Switch Safe diagram:
In Room 5 , the constructor's office, zoom in on the drafting table to the right of the safe to find the diagram for Abraham's Switch Safe.
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Hint: Room 21: Opening the refrigerator safe:
In Room 5, the Kitchen, zoom in on the controls on the refrigerator safe. Use the temperature formulas to calibrate the mechanism to open it. The following temperatures are all equivalent:

10 degrees Celsius

50 degrees Fahrenheit

283 degrees Kelvin

Hint: Room 46:
In Room 46, the music chamber, there are various musical instruments in this room which are played when selected. Zoom in on the tape recorder on the north side of the room and select the "FORW" button to play the fourteen notes of "Twinkle, Twinkle Little Star". Remember the number of notes.